Short fiber reinforced spindle drive wheel

ABSTRACT

A drive wheel is used to rotate a texturizing spindle at high speed. The drive wheel is made from a rubber compound containing extremely short reinforcing fibers and a controlled formulation which provides the drive wheel with a modulus of elongation such that the drive wheel will not distort on its outer drive surface at very high speeds.

United States Patent Burkey et al.

[ Sept. 23, 1975 SHORT FIBER REINFORCED SPINDLE DRIVE WHEEL Inventors: David J. Burkey, Millersville;

William L. Mason, Willow Street;

Robert S. Olcott, Jr., Millersville, all of Pa.

Armstrong Cork Company, Lancaster, Pa.

Filed: Jan. 30, 1974 Appl. No.: 437,829

Assignee:

U.S. Cl. 260/17.2; 74/214; 139/196; 260/17.4 BB; 260/17.4 CL

Int. Cl C08g 51/18 Field of Search 260/172, 17.4 CL, 17.4 BB, 260/844, 845; 139/196; 74/215, 214

References Cited UNITED STATES PATENTS 7/1922 Egerton 74/215 1,578,525 3/1926 Ireland 74/214 2,861,964 11/1958 DeGaugue 260/174 3,171,520 3/1965 Haines 74/214 3,344,094 9/1967 DeGaugue 260/38 OTHER PUBLICATIONS Rubber Age, Sept. 1950, Basic Effects of Wood Cellulose as a Filler in Rubber," Goodloe et al., pp. 687690.

Primary Examiner-Melvin Goldstein Assistant ExaminerEdward Woodberry [57] ABSTRACT 2 Claims, No Drawings SHORT FIBER REINFORCED SPINDLE DRIVE WHEEL BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a drive wheel for false twist spindles of false twist texturizing machines.

2. Description of the Prior Art A typical drive wheel for driving a false twist spindle or spindlette is disclosed in U.S. Pat. No. 3,613,467. Therein the drive wheel has a rigidcore with a urethane coating thereon, which urethane coatingcontains reinforcing'elements of a high tenacity material in whisker form. This patent discloses the typical prior art drive wheel structure. I

The problem that has been encountered with the prior art drive wheel structure is that at very high speeds, the urethane coating tends to melt resulting in a breakdown of the operation of the drive wheel and spindle.

SUMMARY OF THE INVENTION One or two spindle drive wheels are utilized to drive a spindlette structure for providing a false twist in yarn. The spindlette is driven at very high speeds which means that'the drivewheel may be driven at rotational speeds which could exceed50,000 rpm. It is necessary that the driving surface of the drive wheel have a sufficiently high coefficient of friction to drive the spindlette reliably and, at the same time, have a modulus of elongation such that the drive wheel will not distort on its outer driving surface or become loose on the bearing shaft which supports it and holds it in alignment with the spindlette. It was found that a very high resistance to dimensional change at low elongation is accomplished by incorporating extremely short cellulose fibers into the composition of the drive wheel. In addition, there was the controlled use of a reinforcing resin and other ingredients in the composition so as to provide desirable performance properties. By a proper balancing of the various factors, it was possible to provide a drive wheel with sufficient resistance to elongation so that it would not be distorted at high speedusages without the need of providing the drive wheel with an extremely hard structure so that it would lose its ability to frictionally drive the spindlette. Normally, increased resistance to elongation goes along with increased hardness of the rubber and increased hardness of the rubber normally means a lessening of the coefficient of friction which results in substantial slippage between the drive wheel and the spindlette.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the textile texturizing industry, yarn is processed through a magnetically supported twist tube known as a spindlette. The spindlette is rotated at a very high speed anywhere from 200,000 to 1,000,000 rpm. by the means of a friction drive element known as the spindle drive wheel. Normally, the spindle drive wheels are used in pairs, one being driven by a belt with the spindlette held in a nip between the two drive wheels with the second drive wheel being driven by contact with the spindlette. The ratio of the speeds of drive wheel to spindlette is anywhere from 2.5/35 to 3/35, so that the drive wheel rotational speed could exceed 50,000 rpm. With conventional urethane surface covered drive wheels, a problem has been encountered in that at high speeds, the urethane tends to melt. Certain rubber compounds can be used to overcome the melting problem. However, these rubber compounded drive wheels must provide a driving surface with a sufficiently high coefficient of friction to drive the spindlette reliably and, 'at the same time, have a modulus of elongation such that the drive wheel will not distort on the outer driving surface against the spindlette or become loose on the bearing shaft which supports the drive wheel and holds it in alignment. Naturally, it happens that the desired modulus of elongation can be secured normally with a lowering of the coefficient of friction. Consequentlyfit has become necessary to develop a drive wheel with two characteristics which tend to be reciprocals of each other.

Several attempts were made to reinforce rubber base drive wheels with a number of fibers of various lengths and different compositions. It was hoped that by fiber reinforcement an apparently low modulus composition could be secured with a high resistance to dimensional change. It was found that satisfactory results could only be secured through the use of extremely short cellulose fibers which are sold under the trade name of Solka Floc, a trademarked product of the Brown Company of Milton Village, Massachusetts. This is a wood cellulose flock fiber material which is useful herein only when it ranges in length from 76 microns to I50 microns. The diameter of the fiber is approximately onesixth of the length of the fiber.

When a satisfactory dispersion of the cellulose fiber was obtained in the rubber matrix, there resulted a product which had a very high modulus at low elongation. Such a product alone still tended to be subject to some chipping and burning in use. Consequently, the composition was modified by the use of a reinforcing resin and a semi-reinforcing carbon black and also by an altering of the vulcanizing ingredients. This then yielded a product which would provide the desired performance properties. A typical formulation which resulted in a superior product is as follows:

Parts by Weight The above formulation was compounded in the following manner. A water slurry of Solka Floc SW-40 fibers was prepared with the fibers being 13% of the slurry solution. The particular Solka Floc SW-40 fibers were approximately 100 microns in length by 16 microns in thickness. It is a wood cellulose flock fiber which has a bulk density ranging from 5.7 to 10 pounds per cubic foot. The parts by weight of Solka Floc" were dispersed in the water and approximately 35 to 55 parts of alum was added thereto. The parts by weight of latex was then added and the mix was stirred four to five minutes with the addition of a slight amount of ammonia to adjust the ph to 7.5 to 8.0. The alum caused the precipitation of the latex onto the cellulose fibers. The particular latex being used in the above example was Chemigum 2716E which is made by the Goodyear Company. This particular latex is a butadiene-acrylonitrile latex (30-35% by weight acrylonitrile). Once the latex is fully precipitated on the fibers, the slurry is drained and sheeted. The sheets are then permitted to dry. Other medium (28-35%) acrylonitrile content latex materials may be substituted for the above latex.

The resultant latex and cellulose fiber material is then added to a Banbury mixer. There is also added to the Banbury mixer the zinc oxide which operates as an activator for curing the rubber compound, the stearic acid which functions as a lubricant and the carbon black which is semi-reinforcing furnace black. The above ingredients are then blended for approximately minutes in the Banbury mixer to 200 to 300F. The resulting mix is then dropped on a consolidating roll structure which sheets the mix to permit its cooling.

Once the above mix has cooled, it is banded on a conventional mixing mill. At this time, there is added the sulphur, the Santocure and the reinforcing resin. Santocure is a trademarked product of Monsanto Chemical Company. It is chemically a N-Cyclohexyl-Z- benzothrazolesulfenamide. It is used as an accelerator for the curing of the rubber compound and other conventional accelerators can be used. The reinforcing resin is Durez 12687, a trademarked product of Hooker Chemical Company. This is a phenolformaldehyde thermosetting resin which is a mixture of a thermoplastic phenolic formaldehyde condensate product with 8% hexamethylenetetramine. The total formulation is then mixed for ten to twenty minutes on a mixing mill. From the mixing mill, it is then fed to a conventional extruder which extrudes the formulation into rods. The rods are then vulcanized for 2 hours at 350F. in open steam to form the vulcanized rubber product. This will then be formed into the rubber porfrom 1 to 10 partsby weight while the accelerators can vary in range anywhere from /2 to 4 parts by weight'of the rubber. Finally, it is possible to vary in range the semi-reinforcing furnace black anywhere from 20 to 100 parts by weight. This degree of flexibility will exist because the cellulose fibers naturally come in various lengths and as their lengths vary, so do their reinforcing characteristics. The essence of the invention lies in the use of extremely short cellulose fibers in a low-modulus composition with a high resistance to dimensional change at low elongation.

Using a rubber compound without the fibers will yield a product with a Shore D hardness of 55-65 with a satisfactory low elongation modulus. The incoporation of the fibers lowers the Shore D hardness 5-10 points at the same'low elongation modulus. Thus, there is secured a softer product with better frictional drive at a comparable modulus. Using a commercially available solid urethane drive wheel and driving a spindlette at 450,000 to 600,000 rpm., the urethane drive wheel was surface melted in 5 minutes. Using a drive wheel of the above invention under the same test conditions, there was no apparent failure after several weeks running.

What is claimed is: v

1. A spindle drive wheel for driving a false twist spindlette, said drive wheel being rod shaped and being formed from a vulcanized butadiene-acrylonitrile rubber composition which contains extremely short fibers- Parts by weight (DE!) Latex (butadiene-acrylonitrile) Solka Floc (short fibers [76-l50 microns] of cellulose material) 50-100 Phenol-Formaldehyde Reinforcing Resin 20-70 Sulfur l-lO Santocure (N-Cyclohexyl-Z-benzothrazole-sulfenamide) l/2-4 Carbon Black 20-100. 

1. A SPINDLE DRIVE WHEEL FOR DRIVING A FALSE TWIST SPINDLETTE, SAID DRIVE WHEEL BEING ROD SHAPED AND BEING FORMED FROM A VULCANIZED BUTADIENE-ACRYLONITRILE RUBBER COMPOSITION WHICH CONTAINS EXTREMELY SHORT FIBERS OF WOOD CELLULOS MATERIAL HAVING A LENGTH RANGING FROM 76 MICRONS TO 150 MICRONS, SAID RUBBER COMPOSITION BEING APPROXIMATELY 100 PARTS BY WEIGHT WITH SAID CELLULOSE MATERIAL BEING APPROXIMATELY 50-100 PARTS BY WEIGHT,
 2. A friction material of improved wear life at drive speeds of 450,000 to 600,000 rpm''s consisting essentially of 